Polarization preserving projection screen with engineered particle and method for making same

ABSTRACT

Polarization preserving projection screens provide optimum polarization preservation for 3D viewing. The projection screens additionally provide improved light control for enhanced brightness, uniformity, and contrast for both 2D and 3D systems. Generally, the disclosed method for providing a projection screen comprises embossing at least a first side of a first substrate to produce an optically functional material and then cutting the optically functional material into pieces to produce a plurality of engineered particles. The plurality of engineered particles may then be deposited on a second substrate to produce a substantially homogeneous optical appearance of the projection screen.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 61/289,346, filed Dec. 22, 2009, entitled “Polarizationpreserving projection screen with engineered particle,” the entirety ofwhich is herein incorporated by reference. This application is filedconcurrently with U.S. patent application Ser. No. 12/977,026, entitled“Polarization preserving projection screen with engineered pigment andmethod for making same,” which claims priority to U.S. Prov. Pat. App.Ser. No. 61/289,343, filed Dec. 22, 2009, entitled “Polarizationpreserving projection screen with engineered pigment,” the entirety ofwhich are herein incorporated by reference.

TECHNICAL FIELD

The present disclosure generally relates to front projection screens,and more specifically, to polarization preserving front projectionscreens.

BACKGROUND

Modern three-dimensional (“3D”) cinema systems increasingly rely onpolarization as a means of delivering stereoscopic imagery to anaudience. Most of these systems place polarization control elements atboth the digital projector and the viewer, which in practice makes thescreen a contrast and/or cross-talk determining component. Manufacturersof front projection screens generally attempt to strike a compromisebetween image brightness uniformity and Polarization Contrast Ratio(“PCR”). Relative lack of efficiency of current screens (which has beendescribed as Total Integrated Scatter or “TIS”), along with inherentlight loss of most 3D delivery systems, further call for high peak gainto meet standards for image brightness. Conventional “silver-screens,”however, have performance deficiencies that are the result of severalstatistical variables, which make it virtually impossible to optimizePCR, gain profile and efficiency.

BRIEF SUMMARY

According to the present disclosure, a method for providing a projectionscreen may include embossing at least a first side of a first substrateto produce an optically functional material, cutting the opticallyfunctional material into pieces to produce a plurality of engineeredparticles and depositing the plurality of engineered particles on asecond substrate to produce a substantially homogeneous opticalappearance of the projection screen. The method may include embossing asecond side of the first substrate to produce the optically functionalmaterial. The embossing on the first and second side of the firstsubstrate may be substantially similar pattern or may be differentpatterns. The embossing may approximately hold a predeterminedtolerance, wherein the predetermined tolerance may be based on at leasta difference between long-range statistics and ensemble statistics ofthe projection screen. Additionally, depositing the plurality ofengineered particles on the second substrate may provide a surface onthe second substrate that substantially approximates the statistics ofthe embossed first substrate.

Disclosed in the present application is a projection screen with asubstantially homogeneous appearance, wherein the substantiallyhomogeneous appearance may be achieved through web shuffling. Theprojection screen may include a first substrate and a coating adjacentto the first substrate. The coating may include a plurality ofengineered particles which may be produced by cutting an opticallyfunctional material into pieces and the plurality of engineeredparticles may be operable to primarily determine the scattering behaviorof light and may be within a predetermined size range. The first side ofthe optically functional material may be embossed and/or the second sideof the optically functional material may be embossed. Additionally, thecoating may further include a surface operable to decouple the scatterprofile from the polarization contrast ratio of the projection screen.

According to another aspect, the present application discloses a methodfor providing a projection screen. The method may include embossing atleast a first side of a first substrate and embossing at least a firstside of a second substrate. The method may further include laminatingthe first substrate and the second substrate together to produce anoptically functional material. The optically functional material may becut into pieces to produce engineered particles and the engineeredparticles may be deposited on a third substrate to produce asubstantially homogeneous optical appearance of the projection screen.Additionally, the embossing on the first of the first substrate and thesecond side of the second substrate may produce substantially similarpatterns. The embossing may hold a predetermined tolerance, wherein thepredetermined tolerance may be based on at least a difference betweenlong-range statistics and ensemble statistics.

These and other advantages and features of the present invention willbecome apparent to those of ordinary skill in the art upon reading thisdisclosure in its entirety.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments are illustrated by way of example in the accompanyingfigures, in which like reference numbers indicate similar parts, and inwhich:

FIG. 1 is a schematic diagram illustrating the cross section of aconventional silver screen structure;

FIG. 2A is a schematic diagram illustrating a cross section of oneembodiment of a structure for a projection screen, in accordance withthe present disclosure;

FIG. 2B is a schematic diagram illustrating a cross section of oneembodiment of a structure for a projection screen, in accordance withthe present disclosure;

FIG. 3 is a schematic diagram illustrating one embodiment of a processfor providing engineered particles, in accordance with the presentdisclosure;

FIG. 4 is a schematic diagram illustrating a spectrum of feature sizesand the ranges associated with particular screen characteristics, inaccordance with the present disclosure;

FIGS. 5A and 5B are schematic diagrams respectively illustrating oneembodiment of a defect before and after web shuffling, in accordancewith the present disclosure; and

FIG. 6 is a flowchart illustrating operations of one embodiment of amethod for providing projection screens, in accordance with the presentdisclosure.

DETAILED DESCRIPTION

Generally, one embodiment of the present disclosure may take the form ofa method for providing a projection screen using web shuffling. In thisembodiment, the method may be achieved by embossing a substrate tocreate an optically functional material, creating particles of anapproximate size range appropriate for the selected coating technologyby dicing the optically functional material, and re-coating theparticles on a screen substrate. In one exemplary embodiment, theparticles may be diced diffuser particles and may be substituted forball-milled aluminum typically used in a conventional spray paintingprocess. In another exemplary embodiment, a virtually deterministicengineered particle with prescribed scatter statistics may relyprimarily on web shuffling for the randomization needed to create asubstantially macroscopic homogeneous appearance.

Another embodiment of the present disclosure may take the form of aprojection screen with a substantially homogeneous appearance which maybe achieved via web shuffling. The projection screen may include asubstrate which may be coated with an optically functional material thatincludes engineered particles. The engineered particles may be createdby dicing double-side coated diffuser material on a carrier substrate.The diced, engineered particles may then be deposited on a screensubstrate to create a substantially homogeneous optical appearance ofthe screen substrate.

Yet another embodiment of the present disclosure may take the form of aprojection screen with a substantially homogeneous appearance which maybe achieved via web shuffling. The projection screen may include asubstrate which may be coated with an optically functional material thatincludes engineered particles. The engineered particles may be producedby dicing a laminated structure. The laminated structure may include afirst and second substrate with embossed layers on the outer surfaces ofthe laminated structure. The engineered particles may then by depositedon a third substrate to produce the substantially homogeneous opticalappearance of the projection screen

It should be noted that embodiments of the present disclosure may beused in a variety of optical systems and projection systems. Theembodiment may include or work with a variety of projectors, projectionsystems, optical components, computer systems, processors,self-contained projector systems, optical systems, visual and/oraudiovisual systems and electrical and/or optical devices. Aspects ofthe present disclosure may be used with practically any apparatusrelated to optical and electrical devices, optical systems, presentationsystems or any apparatus that may contain any type of optical system.Accordingly, embodiments of the present disclosure may be employed inoptical systems, devices used in visual and/or optical presentations,visual peripherals and so on and in a number of computing environmentsincluding the Internet, intranets, local area networks, wide areanetworks and so on.

Before proceeding to the disclosed embodiments in detail, it should beunderstood that the invention is not limited in its application orcreation to the details of the particular arrangements shown, becausethe invention is capable of other embodiments. Moreover, aspects of theinvention may be set forth in different combinations and arrangements todefine inventions unique in their own right. Also, the terminology usedherein is for the purpose of description and not of limitation.

FIG. 1 is a schematic diagram illustrating the cross section of aconventional silver screen structure 100 used for stereoscopic 3Dimaging. The conventional silver screen 100 may include a substrate 110and a coating 120. Generally, conventional silver screens 100 may befabricated by spray-painting the coating 120 onto the substrate 110. Thecoating 120 may include resin 130, aluminum flake 140 and matting agents150. The flake 140 may be immersed in a transparent binder such as resin130. Additionally, the aluminum flake 140 may be ball-milled aluminumparticles or pigment. The matting agents 150 may be any type of particleto produce the desired optical characteristics and may be particles suchas silica.

Various optical characteristics, either qualitative or quantitative, maybe used to evaluate the optical performance of a projection screen suchas the conventional silver screen 100. The optical characteristics mayinclude measurements such as, but not limited to PCR, scatter profile,TIS, scattering from individual components of the projection screen,image brightness, image brightness uniformity, gain, gain profile and soon. The optical characteristics will be discussed in further detailbelow. The evaluation of conventional silver screens illustratesperformance deficiencies with one or more non-optimized, aforementionedoptical characteristics.

For example, conventional silver screens, generally, may demonstrate anon-axis circular PCR of 90:1 and may rarely exceed 120:1. The less thanoptimal on-axis circular PCR may be attributed to poor performance ofthe raw materials such as the substrate 110 and lack of process controlwhen fabricating one or more of the coating 120, the aluminum flake 140or resin 130. Additionally, the cross-talk term is characteristicallyangle neutral, so the PCR may also tend to degrade in proportion to thegain curve. The result may be screen performance that drives systemlevel PCR and thus may dictate the quality of the stereoscopic 3Dexperience. System level PCR may be composed of the combined effect ofmost or all of the components. Currently, the system level PCR may beprimarily determined by the screen PCR.

In FIG. 1, the individual components of the conventional silver screen100 may contribute to the optical characteristics. For example, thealuminum flake 140 may serve as statistical scatterers, thus, whencombined with the statistics of particle stacking may determine themacroscopic scatter characteristics of the conventional silver screen100. Although low-cost ball-milled aluminum particles may beneficiallybroaden the scatter profile due to the relatively irregular shape/sizeof the aluminum particles, the aluminum particles may cause other issuesfrom a polarization management perspective. When the previouslydiscussed issues are coupled with the statistics associated with thecoating process, current screen manufacturing may lack the controlrequired to increase the diffusion angle without compromising PCR. Morespecifically, as the probability of a highly sloped surface increases,so too does the probability of a secondary reflection event, with thePCR suffering as a consequence.

One aspect of the present disclosure addresses the previously discussedlimitations and may use a novel “web shuffling” technique in conjunctionwith roll-to-roll fabricated diffuser. Web shuffling is an averagingprocess, whereby engineered particles of a prescribed size may betransferred from a carrier substrate to a screen substrate using astatistical (or shuffling) process. According to the present disclosure,the shuffling process may be used to substantially homogenize one ormore non-uniformities that may occur in the manufacturing of the rawdiffuser stock. In one example, it may be understood thatnon-uniformities are substantially homogenized when the human eye cannotdetect the non-uniformities at one or more of the following scales: justresolvable dimension, just resolvable area, just noticeable differenceand so on. Each of the particle size and morphology, or both, may beoptimally selected such that each may provide a suitable approximationto the desired macroscopic scatter statistics. The particles may bemanufactured using roll-to-roll embossing technology, which produces theimproved optical quality reflective diffuser performance. The webshuffling of the present disclosure may allow for the elimination of theneed to manufacture roll-to-roll embossed diffuser on a wide-web that issubstantially defect-free and extremely uniform.

The technique of web shuffling enables the substantial homogenization ofsubtle non-uniformities that can result in the tooling fabrication,roll-to-roll manufacturing process, and vacuum optical stack coating,without significantly sacrificing optical performance. The benefits ofthis approach for screen manufacturing can take many forms, including,but not limited to: (1) Spatially averaging large scale variations indiffuser profile characteristics; (2) Azimuthally averaging the effectsof a directional diffuser (which can also vary spatially); and (3) froma yield standpoint, spatially averaging (or removing) gross defectmaterial, which can include drum seams, large facets, scuffs, and othermacroscopic defects in the embossing and optical coating process.

A benchmark for stereoscopic 3D front projection screen performance isan engineered surface with a highly reflective (e.g. aluminum) conformallayer, as described in the commonly-owned U.S. Patent ApplicationPublication No. US 2009/0190210, which is hereby incorporated byreference. An engineered surface can be generated directly from asurface map file or a set of design rules, and thus can in principleprovide a virtually ideal scatter profile, PCR, and efficiency. However,the fabrication of such a surface in sufficient size to build a cinemascreen can be challenging.

In one example, the fabrication of the previously discussed surface mayinvolve fabricating and maintaining a roll-to-roll embossing tool thatmay have one or more of the following features: 1) no drum-seams or nosubstantially significant drum-seams; 2) no gross defects orsubstantially insignificant gross defects either of which would avoidproducing repeating screen artifacts (e.g., voids that producemirror-like facets); and/or 3) a prescribed topography that isstatistically uniform over the entire tool. In order to avoid visuallyobjectionable diffraction artifacts and moire, the ideal design may alsoincorporate feature randomization (versus a true periodic structure onthe roll-to-roll embossing tool). Moreover, the scatter statistics atthe web edges must be well matched, so that butt joinedstrips of film donot produce substantial visible intensity steps (when observing frommost or all locations in a theatre).

Given the scale and cost of the raw diffuser stock, acceptable yield maybe obtained if cosmetic defects resulting from the manufacturing andhandling of the material are virtually eliminated. Tighter statisticscan be obtained by using higher quality leafing pigments, which areoptically flatter and tend to align in the plane of the binder surface.However, surfaces made with optical quality flat metallic leafingpigments have inherently narrow scatter profiles (e.g., 5-15 degreehalf-power angle), producing screens with higher TIS, but poorbrightness uniformity. Furthermore, methods for broadening the scatterprofile of optical quality pigment by controlling the extent of leafingoften lack manufacturing robustness. Although a non-leafing pigment maybe used, non-leafing pigment typically produces more of a bulk scatter,which is difficult to control and is again at the expense of PCR.Importantly, web shuffling in conjunction with roll-to-roll fabricateddiffuser may address the limitations of both these technologies.

FIGS. 2A and 2B are schematic diagrams illustrating a cross section ofembodiments of a structure for a projection screen, in accordance withthe present disclosure. FIG. 2A depicts a web-shuffled chop screen 200which includes a substrate 210 and a web-shuffled coating 220. Theweb-shuffled coating 220 may include a fluid 230. The fluid 230 maycontain a transparent binder resin such as, but not limited to PVCresin, enamel, polyurethane, acrylic, lacquer, and the like, and/or someform of dilution, which can be either solvent or aqueous based. Thefluid 230 may serve as a carrier for the chop particles 240. The chopparticles 240 may be engineered aluminum flakes or particles createdfrom at least one or more of an embossed layer, a reflective coating andoptical coatings. As illustrated in the embodiment of FIG. 2A, the chopparticles 240 may be randomly distributed throughout the web-shuffledcoating 220 such that the chop particles 240 may or may not beoverlapping. Additionally, the chop particles 240 may be in theapproximate size range of 100 microns to over five millimeters.

Additionally, FIG. 2B depicts a web-shuffled chop screen 200 b whichincludes a substrate 210 b and a web-shuffled coating 220 b. Theweb-shuffled coating 220 b may include a fluid 230 b. The fluid 230 bmay contain a transparent binder resin such as, but not limited to PVCresin, enamel, polyurethane, acrylic, lacquer, and the like, and/or someform of dilution, which can be either solvent or aqueous based. Thefluid 230 b may serve as a carrier for the chop particles 240 b. Thechop particles 240 b may be engineered aluminum flakes or particlescreated from at least one or more of an embossed layer, a reflectivecoating and optical coatings. As illustrated in the embodiment of FIG.2B, the chop particles 240 b may be distributed throughout theweb-shuffled coating 220 b such that the chop particles 240 b may or maynot overlap. Additionally, the chop particles 240 b may be in theapproximate size range of 100 microns to over five millimeters. Thefabrication of the web-shuffled chop screens 200 and 200 b will bedescribed in detail below. Furthermore, in FIGS. 2A and 2B, the chopparticles may be distributed such that the surface of the web-shuffledchop screens 200 and 200 b may have little to no area between the chopparticles.

FIG. 3 is a schematic diagram illustrating one embodiment of a processfor providing engineered particles, in accordance with the presentdisclosure. FIG. 3 depicts one embodiment of a fabrication process 300that may be used to create the chop particles 240 of FIG. 2. FIG. 3includes a substrate 310, embossed layer 320, reflective layer 330 andoptical coating 340. The embossed layer 320 may be fabricated from aninitial continuous surface (not depicted in FIG. 3). Additionally, theinitial continuous surface and embossed layer 320 of FIG. 3 may bemeasured and evaluated using similar functional specifications, each ofwhich will be discussed below.

In one embodiment of a different fabrication process than the processdepicted in FIG. 3, the first substrate may be coated on a first sideand not on the second side. To clarify, the first side of the firstsubstrate may include an embossed layer, a reflective layer and anoptical coating, but the second side of the first substrate may notinclude any of the aforementioned layers. Additionally, a secondsubstrate may include an embossed layer, a reflective layer and anoptical coating on a first side of the second substrate. The firstsubstrate and the second substrate may be laminated together such thatthe coated sides of the substrates face in an outward direction.Furthermore, the fabrication of the initial continuous surface will bediscussed in further detail below.

The light scattering behavior of a surface fabricated according to thepresent disclosure may be the result of several statistical processes.Generally, the compound statistics may be the result of threemanufacturing process steps; (1) Fabrication of the initial continuoussurface, (2) Fabrication of discrete surface elements, and, (3) Coatingof discrete surface elements. The following describes the fabricationprocesses and the parameters influencing first-order statistics, as wellas embodiments that most closely approximate the behavior of the idealsurface.

Fabrication of Initial Continuous Surface

The initial surface may be fabricated using a number of manufacturingprocesses that substantially produce a predetermined topography. Thepreferred topography may be optically smooth, with slopes that varyspatially on a scale that is large relative to a wavelength ofilluminating radiation. In one embodiment, the initial surface may bemastered using an analog photo-resist process, from which manufacturingtooling is generated. The fabrication of the manufacturing tool may alsoinclude intermediate tooling steps in addition to the analogphoto-resist process. Additionally, there may be certain limitations tothe nature of surfaces and associated statistics that may be realizedwhen employing the analog photo-resist process, as in the case ofoptical recording of speckle patterns. In another example,direct-laser-recorded analog photo-resist processes may permit surfacesto be engineered, with fidelity limited primarily by the resolution ofthe laser spot and the characterization/repeatability of the opticalrecording transfer function.

Functional Specifications of Initial Continuous Surface and Diffuser

Design rules for achieving optimal performance for continuous surfaces(subject to specific theatre geometry) and as described in U.S. Pat.App. Pub. No. 2009/0190210 may be applied to produce the initialsurface. In the case of a polarization-preserving front-projectionscreen and also as described in U.S. Pat. App. Pub. No. 2009/0190210,the desired functional specifications are well defined. In principle, solong as the functional specifications are substantially satisfied, thedetailed distribution of surface topography is of no specificimportance. The functional specifications may include, but are notlimited to, PCR, gain profile shape, and visual appearance. Theexception may include designs incorporating azimuth dependence, which islost in the web shuffling process. Some basic characteristics of desiredsurfaces are described herein.

For naturally occurring diffuser surfaces, for example, non-engineeredsurfaces, the characteristics are frequently determined by physicallymeasuring the bi-directional reflectance distribution function (“BRDF”),representing the differential reflectivity per solid angle. Suchmeasurements can also be made with polarization sensitivity, giving aPCR profile. When a BRDF measurement is made over a sampling area thatis large relative to the mean feature size of a scattering unit, theresult may be a relatively smooth profile. Many such surfaces may havethe desirable characteristics of a matte appearance and nearlyLambertian distribution, as the light collected by the eye is the resultof many scattering events from features that are at/below the wavelengthscale. This randomization may be beneficial by creating a uniformappearance (which may include elimination of optical affects due to thespatial coherence of the source at the screen), but may inefficientlyuse light, and may have a negative impact on polarization preservation.

For the subset of diffuser surfaces that preserve polarization well,there may be a close correspondence between the slope probabilitydensity function and the BRDF. This is because virtually all lightreflected by the diffuser is the result of single scattering events. Aviewer receives light from appropriately oriented contours of thesurface which represent mirror-like specular reflections. To the extentthat the angles are reasonably small (so that the differences betweencomplex S and P reflections can be neglected), such interactionscompletely preserve the state of polarization locally. Also, selectionof feature size and distribution may be important to avoid the grainyappearance (particularly at large observation angles) associated withlow spatial density of appropriately sloped surface. This may be also animportant consideration in the specular direction, where superpositionof partially coherent light can cause speckle. One aspect of the presentdisclosure seeks to utilize web shuffling to capitalize on the surfacecontrol available in processes, such as UV embossing, for creatingoptimized surfaces.

Fabrication of Discrete Surface Elements

The fabrication of discrete surface elements may introduce a secondstatistical process. This process may affect the resulting screenbehavior primarily through the statistics of particle size, and inparticular, the size of particles relative to other characteristicfeatures.

According to one aspect of the present disclosure and returning to FIG.3, the embossed layer 320 may be diffuser roll-stock and may befabricated using various processes such as, but not limited toroll-to-roll UV embossing, UV casting, thermal embossing and so on. Theembossing process may be followed by vacuum deposition of at leastreflective layers and optical coatings.

In one embodiment of the present disclosure, a thin substrate (e.g. inthe approximate range of one micron to 200 microns) may be used toensure minimal particle depth. The embossing may be on opposite sides ofthe substrate, or alternatively, a pair of single-side embosseddiffusers may be laminated together. The former is advantageous from thestandpoint of cost and overall thickness. Double-side UV embossing maybe done sequentially, as access to one side of the web may be requiredfor curing the UV coating. In one example, the UV coating may beacrylic. Additionally, technologies such as hot embossing may permit aone-step embossing process. In one exemplary embodiment, identicalsimilar diffuser surface may be embossed on both sides of the substrate,and in another embodiment, a unique pattern may be embossed on eachside. Relative to the latter, it may be anticipated that the subsequentcoating process produces a spatial averaging of the two diffuser typesto substantially produce a desired composite behavior.

The double-side diffuser may be subsequently double-side coated with ahighly reflective (e.g. aluminum) coating, which may preferably beconformal to the underlying diffuser surface. Some embodiments mayfurther involve coating the aluminum with a thin dielectric to passivatethe aluminum. However, the diffuser may be anticipated to be protectedfrom abrasion and chemicals by a dielectric overcoat, or binder, appliedin a subsequent wet coating process step. In an exemplary embodiment thesubstrate refractive index may be approximately matched to that of thebinder, thus substantially eliminating reflections from the substratewalls.

The net thickness of the raw diffuser stock may include the substrate,and the maximum combined thickness of the UV (e.g. acrylic) coatings.The thickness of the reflective coatings, which may be in theapproximate range of 1,000-2,000 Angstroms, can be neglected. Assuming adiffuser with small feature sizes, the peak-to-valley height of thestructure, along with a reasonable thickness of underlying material, mayrepresent an approximate, effective thickness range of five to tenmicrons. As such, the particles may be manufactured with an approximatethickness range of 20-30 microns. Although the material may be highlyflexible, and while it may have some distortion and curl whenfree-standing, it may conform to a screen substrate in subsequent wetcoating.

After completing the optical coatings, the raw-diffuser stock may bechopped into small particles using, for example, conventional roll-diecutting processes. In some embodiments, one may choose a cutting processthat reduces chipping of the diffuser coating at the perimeter. Thechipping of the diffuse coating may produce a specular reflection fromthe exposed substrate in the absence of a binder over-coat. Moreover, inone embodiment, the chosen cutting process may produce vertical wallsthat are substantially smooth and free of cracks in order to minimizethe potential impact of the walls on optical performance. Desirable sizeand geometry of a particle may depend upon one or more of the desiredoptical appearance, the context in which the screen is used (e.g. thevisually resolvable area), the approximate characteristic dimension of afeature that web-shuffling is to homogenize, and the parameters of theparticle coating process. In an exemplary embodiment, the material maybe chopped into approximately hexagonal particles roughly one mm insize. In a cinema environment, this size may be appropriate consideringthe relative dimension of other features (e.g. a pixel of a digitalprojector is several millimeters in size, and there are acousticthrough-holes, with roughly 1 mm diameter, neither of which isresolvable from a reasonable distance).

FIG. 4 is a schematic diagram 400 illustrating a spectrum of featuresizes and the ranges associated with particular screen characteristics,in accordance with the present disclosure. FIG. 4 includes a spectrum400 of feature sizes and the ranges associated with particular screencharacteristics. Diffuser feature size 410 may be configured to besignificantly larger than a wavelength of illuminating radiation inorder to assure that polarization can be locally preserved in reflectionas indicated by the local statistics range 420. Within a range ofdiffuser feature sizes, interactions of light with the surface aredescribed by specular reflections, in the long range statistics 440,with behavior accurately predicted by Fresnel's equations. When probinga surface at the long range statistics 440 scale (and moderately above),statistical scatter profiles are sparsely distributed (converging todeterministic at the extreme low-end) as they represent the mostlocalized events. As the probe area increases, the scatter statisticsbecome more complete and thus begin to describe the character of themacroscopic surface. At a preferred particle size within the particlefeature size range 430, each unit may capture long-range statistics,where the scatter profile may be smooth and may be similar to a measuredscatter profile obtained by probing a significantly larger area.

At still larger scales, such as the range of ensemble statistics 450,there may be visually resolvable defects, drift, and distortions to thescatter profile. These visually resolvable defects may be due to lack ofprocess control in manufacturing both the tooling and the base material.Moreover, the diffuser can have directionality, which may also driftspatially. As such, there may be significant statistical variationbetween particles. In this case, it may be preferred that particles aresmall relative to the scales at which the eye can just begin to resolvestructure. The scales at which the eye may begin to resolve structuremay be referred to as a just-resolvable-dimension (“JRD”), orjust-resolvable area (“JRA”). The latter may ensure that the screen doesnot exhibit significant granularity at the scale of a particle.

The ensemble may represent a significant number of possible outcomesmeasured at the scale of a finished screen. This may include a largenumber of positions/azimuth angles of the diffuser base material (bothupright and inverted) utilized to produce a finished screen. Sincespatial/azimuthal variations in the scatter profile of the base materialare common, ensemble statistics are broadly distributed relative to anysmaller scale statistics. Differences between ensemble statistics of thebase material and that of the coated screen may be predominantlyassociated with the statistics of the coating process.

According to an exemplary embodiment, a particle may be large enough tocapture long-range statistics, but may be smaller than any visuallyresolvable defect requiring homogenization. Such defects may betypically associated with structure in the screen that producesintensity variations that are small relative to the mean intensity. Inthis limit, suitable particle size may depend upon factors such as, butnot limited to, viewing distance, particle-to-particle statistics, andany contribution from the coating process.

FIGS. 5A and 5B are schematic diagrams respectively illustrating oneembodiment of a defect before and after web shuffling, in accordancewith the present disclosure. FIGS. 5A and 5B include defects onsubstrates 500 and 510, before and after web shuffling, respectively(not illustrated to scale). On substrate 500 (before web shuffling),defects or individual facets 520, 530 may be several hundred microns indiameter, and as such, can potentially be homogenized by web shuffling.Defect 520 may be cut into particles 521, 522, 523 and 524. Although theparticles 521, 522, 523 and 524 are depicted as similarly sizedapproximately hexagonal pieces in FIG. 5, the defects may be cut intoany size and/or shape. Likewise, individual facet 530 may be cut intoparticles 531, 532 and 533 and randomly distributed onto substrate 510,as depicted in FIG. 5B. Additionally, the material surroundingindividual facets 520 and 530 may also be cut into pieces, but forpurposes of discussion only in FIGS. 5 a and 5B, the individual facetsare depicted as such. After web shuffling, and as shown in FIG. 5B,substrate 510 includes particles 521, 522, 523, 524, 531, 532 and 533randomly distributed on the substrate 510.

While defects as illustrated in FIGS. 5A & 5B may not be completelyeliminated at the particle scale, reducing the area of facets canmitigate the impact on visual quality. At a larger scale, clusters ofsuch defects, and clusters that repeat due to flaws in toolmanufacturing, may be likewise homogenized. Clusters of small specularfacets are often associated with the hot-spot effect, which may manifestas a spike in the gain profile along the specular direction. Re-coatingmay provide sufficient tilt randomization to substantially eliminatethis effect.

According to another exemplary embodiment, differences betweenlong-range statistics and ensemble statistics may be held to anapproximate tolerance in the manufacturing of the base diffusermaterial. To reduce or avoid unnecessary texture in the appearance ofthe finished screen, it may be preferred that the observed intensitystep between any two adjacent particles of the ensemble (with anyrelative azimuth orientation) is at or below ajust-noticeable-difference (“JND”). Typically, this may be approximatelyone percent of the mean intensity. Within this approximate range, andneglecting coating contributions to nonuniformity, such a surface mayappear similar to the base diffuser. Web shuffling acknowledges that anintensity step at a boundary between adjacent particles may besignificantly larger, but that the associated texture may not bevisually objectionable provided that the approximate particle size isproperly selected.

In another exemplary embodiment, scatter profiles measured on the scaleof a JRA of the finished screen material may approximately capture theensemble statistics of the raw diffuser. A goal of web-shuffling may beto reduce the scale required to capture ensemble statistics by averagingmaterial in azimuth and position at the scale of a JRA. In a cinemaenvironment, the average such dimension may be on the order ofapproximately one centimeter or larger for a low-contrast structure.

Satisfying the above may depend upon the nature of the defect. Thedefect previously discussed may be physically large, and may berelatively low in amplitude; however, screens can contain other types ofdefects. For example, voids may be produced in UV embossing (or toolmanufacturing) and may be attributed to bubbles. Further to thisexample, when the voids are metalized, the voids may produce highlyreflective facets in the plane of the substrate. While such defects maybe relatively small (on the order of a few hundred microns), and may notbe visually resolvable, the efficiency of the defects may be high in thespecular direction. The result may be a “sparkle”, or localized spike inthe gain profile, that may degrade the homogeneity of the screenappearance. Additionally, clusters of such defects, and clusters thatrepeat, for example, due to flaws in tool manufacturing, may likely besubstantially homogenized.

An important performance metric may be the ratio of particle area tomean diffuser feature area, or particle-to-feature-ratio (“PFR”). ThePFR may be an approximate measure of the ability of a particle tocapture the desired long-range diffuser statistics. A benefit ofparticles manufactured according to the present disclosure may be thatthe particles may be arbitrarily large, whereas metal flake pigments maybe limited in size due to their fragility. In a typical diffuser designthe mean feature size may be approximately twenty microns, which mayyield a PFR for a one millimeter hexagonal particle of over 2,000. In anexemplary embodiment, the mean feature size of the diffuser may be inthe approximate range of ten microns or smaller. The integrated scatterprofile with a PFR of this magnitude may appear smooth and may resemblean integrated scatter profile provided by integrating over substantiallylarger areas.

The minimum feature size possible may depend upon the optical recordingprocess. In an image recording process (e.g. speckle) there may bechallenges to resolving very small speckles due to the quality of theimaging system and opto-mechanical stability issues. Vibrations thatoccur during recording can tend to impact the quality of the master dueto blur. However, it is reasonable to expect that mean feature sizes ofapproximately five microns may be possible with either image (e.g.speckle) recording or direct laser written engineered surfaces. A PFR ofroughly 100 may be adequate to approximately capture the statistics of arandomized surface.

In the case of recording arbitrarily small features, the lower limitwould be approximately one micron, which may ensure that polarization ispreserved on reflection. It may be difficult, however, to employ thelower limit with the coating of discrete particles due to the influenceof hard edges.

An embodiment of the present disclosure may allow particles to bemanufactured while approximately maintaining an optimized size range, asopposed to metal flake pigments which may not be sufficiently thick tobe manufactured and coated in sizes greater than about 50-100 microns.An embodiment of the present disclosure may further allow manufacturingof particles that are substantially similar in size, as opposed to thegenerally broad particle size distribution associated with metal flakepigments. Metal flake pigments with low PFR tend to “slump” when coated,increasing the peak gain, while robbing from the desired scatter intolarger angles. The population of particles of a size near or below adiffuser feature size (PFR<10) can be disruptive when attempting topreserve the base diffuser profile, and PCR.

The in-plane aspect ratio (in-plane dimension divided by thicknessdimension) of particles of the present disclosure may be consistentlylarge for all particles (>30:1), which may ensure minimized disruptionto the local diffuser normal-direction as a consequence of coating. Theflexibility of the particles may further allow the particles to conformto the underlying substrate after drying. Yet another advantage of largeparticles of approximately consistent size may be the minimization ofspatial edge density. The edges of particles may have features that maybe at and/or below that of a wavelength, and as such, light interactingwith these edges may not scatter in a manner that preservespolarization. In a crossed-polarizer microscope arrangement, individualparticles appear brightly outlined, as if the image of the diffusersurface were high-pass spatial filtered. A crossed-polarizer microscopemeasurement allows one to visualize the PCR directly on the surface toidentify the source of crossed polarizer leakage. The scatter from edgesis generally “white” in angle space, such that this contribution to theresulting PCR may tend to follow the gain profile. Metal flake pigmentstypically contain a significant population of low PFR particles, whichmay contribute significantly to the density of such edges, thus causingsignificant loss in PCR. With an optimized coating process, PCR may tendto grow with particle size primarily due to the associated reduction inthe area density of edges.

The present disclosure provides embodiments that may allow for thefabrication of discrete surface elements with substantially optimizedoptical performance. For example, the diffuser particles may bemanufactured in a substantially statistically predictable manner. Whilethe surface is inherently statistical, the PFR may be sufficient toensure that a substantial number of particles approximately capturelong-range statistics. The particles may be large and similar in sizeand/or aspect ratio, such that discretizing the surface may notsubstantially contribute to the degradation in screen gain and contrastperformance. The substantial reduction and/or virtual elimination ofthis contributor may enhance the probability of the final screensubstantially preserving the raw diffuser performance.

Coating of Discrete Surface Elements

A coating process of the present disclosure may produce a surface thatapproximates the surface of the initial continuous diffuser, with theaveraging benefits of web-shuffling. This may be accomplished by using arelatively small number of large particles, in which most of the largeparticles may contain an approximate representation of the long-rangestatistics, and by tiling the large particles on the surface withminimal overlap. The tiling may substantially minimize shifts in theslope statistics due to tipping of particles, while providing highfill-factor (ratio of reflective area to total area), with substantiallyminimal waste of diffuser. Such a surface also may have substantiallyminimal edge density, thus substantially maximizing PCR.

Generally, the coating process may involve mixing the reflectiveparticles into a fluid, containing a transparent binder resin and someform of dilution, in which the dilution may be either solvent or aqueousbased. The mixture can be coated onto the substrate using any number ofmethods known in the art, with spray-painting being the most common.Spray painting may be more effective than printing methods for coatingparticles with larger dimensions.

In conventional projection screen manufacturing, an approximate sizerange of one to two meter wide strips of a plasticized substrate may bewelded together, hung vertically, and stretched onto a frame. Next,spray rigs may raster the position of the gun until achieving adequatecoverage. In one embodiment, the diffuser particles are substituted forball-milled aluminum in a conventional spray painting, or gel-coatingprocess. In an exemplary embodiment, the particles are substantiallylarger in dimension than conventional pigments, thus better capturingthe desired scatter statistics.

The optical properties of the coated surface may depend upon severalstatistical variables, among which, may include, but are not limited to,the geometrical characteristics of the particles, the volume ratio ofpigment to binder (or PBR), dilution, any additional additives such asmatting agents, or flame retardants, and the detailed coatingmethodology.

In one embodiment of the present disclosure, the coating requirementsmay be based on, particle tipping statistics which in turn, may beprimarily determined by intra-pigment topography, with coating being asubstantially statistically predictable process. That is, the goal ofthe coating process may be to substantially minimize the role ofparticle tipping statistics on the scatter profile. An exemplaryembodiment of the coating process may produce a substantially continuousmetal surface at the optical interface, with substantially minimal resinovercoat which may provide mechanical integrity and/or durability. Theoptical interface may be the optically functional layer of particles, orthe layer that actually receives and redirects projector light to theaudience. The optical interface may be configured to be macroscopicallyplanar to avoid depth-related appearance artifacts caused by stacking ofparticles, such as shadowing. In one example, the binder and substratemay be quasi index-matched materials, and the screen may be a randomstack of infinitesimally thin continuous structured metallic patches,slightly tipped with respect to the substrate, that are separated indepth by at least the particle thickness. So in addition to beingsomewhat conformal to the surface micro topography, there may be surfacesteps due to the underlying particle stacking. At normal incidence, theseparation of aluminum in the thickness direction may have relativelylittle impact. However, at large incidence angles, a portion of lightmay guide in the channel between the particles and between the metallayers of individual particles. This guided portion of light mayrepresent a light loss, which may be preferred to any such lightmanaging to propagate toward the audience. For example, the transmissionof light from low optical density aluminum or pinholes would be highlydepolarized. The stray light from such interactions may have asignificant impact on PCR, and in this case, using an absorbing (e.g.,black) diffuser substrate and/or an absorbing screen substrate canmitigate the situation.

In one example, the visual perception of screen structural appearancemay be considered in terms of a just-resolvable-area (“JRA”) of thescreen. A desirable particle size may be small in comparison to a JRA,while capturing long-range statistics as described previously. Thus, aJRA may typically encompass a random stacking of many diffuserparticles. Utilizing web-shuffling, these particles may be randomlydistributed in azimuth, and may originate from random locations on bothsides of the base diffuser. As the JRA of a screen may comprise manyparticles, with varying degrees of tipping and occlusion, the perceivedintensity of scattered light can be described by the appropriatelyweighted average of the probability density function of each element.The perception of texture may depend upon, but is not limited to, theratio of JRA to particle size, subtleness of web azimuth/spatialvariations (or, relationship between long-range and ensemblestatistics), and particle aspect ratio, any or all of which mayinfluence tipping statistics. The screen texture can be considered arandom image, where the particle size may primarily define thefundamental spatial frequency.

The ability to discern screen texture may be limited by the angularresolving power of the vision system optics, and the sensor (retina)resolution. Normal vision corresponds to recognizing letters thatsubtend an angular height of five minutes of arc, with each element ofthe letter subtending one minute of arc. Such tests may be performedusing media with sharp edges, black on white, in a high ambientenvironment. Furthermore, this test may be for that part of the eyecorresponding to the fovea of the retina. Outside of the zone of highestresolution, the visual acuity falls by approximately 50% inapproximately two degrees. Moreover, visual acuity falls in reducedambient lighting environments. The current cinema brightness standard is14 fl for 2D presentation, and as low as 4.5 fl for 3D presentation, sovisual acuity may degrade significantly primarily due to increasedaberrations as the pupil dilates. Finally, visual acuity is a functionof contrast. Subtle random modulation in intensity may be more difficultto resolve than periodic black/white bars. Since the peak sensitivity ofthe eye is at a low spatial frequency of 2-3 cycles/degree, ajust-resolvable spatial frequency (associated with a JRA) shifts long asthe modulation depth is decreased. At approximately 100% sinusoidalmodulation, it may be possible to resolve approximately 7 mm at around12 meters distance, but at approximately 10% modulation, it may only bepossible to resolve approximately 13 mm, and at approximately 2%modulation, it may only be possible to resolve approximately 50 mm.Given the nature of random screen non-uniformities, it may be thusreasonable to assume that a JRA of screen surface may be between one andfive centimeters at a typical cinema viewing distance. At dimensionssmaller than a JRA, there may be a spatial averaging that occurs,associated with the sensitivity weighted modulation transfer function(MTF) of the vision system.

In one exemplary embodiment, azimuth/spatial variations of the ensemblemay be subtle, such that long-range statistics and ensemble statisticsmay be similar. Here, the particle-to-particle variations may begenerally small, so the ratio of JRA to particle area may be of lesserimportance in maintaining a substantially homogeneous appearance.

From the standpoint of producing a screen that is substantially free oftexture and/or appears matte and is substantially homogeneous inappearance at all larger scales, it may be generally preferred thatensemble statistics are virtually captured at the smallest possiblescale. The suitable screen may achieve this at the scale of a JRA, whichin some cases calls for a small particle. A characteristic of suchstatistics may be the tendency toward a scatter profile that is somewhatsmooth and symmetric with respect to the normal.

In the absence of tipping, the net effect of web-shuffling may be abroadening of the diffuser profile on the scale greater or equal to aJRA. However, tipping of particles may introduce another broadeningmechanism. In most coating processes, it may be assumed that theprobability density associated with the axis (about which a particletips when stacked) is substantially uniform in azimuth. Further, such aprobability distribution may be virtually achieved at the scale of aJRA, and if so, the scatter profile at this scale may be virtuallysymmetric with respect to the normal. Additionally, it can be assumedthat the direction of tipping may be substantially uncorrelated with theparticle surface structure, which is reasonable given the nature ofthese particles. Under these conditions, the overall scatter profile maybe given by the convolution of the spatial/azimuth averaged profile withthe particle tipping angular distribution. Again, the tendency may befor tipping to broaden the scatter distribution.

Additionally, particles may be sufficiently rigid that they stackwithout bending, and in this case, there is a fixed tipping angle foreach element. Alternatively, the forces on the particle may be high inthe drying process, and the particles may be very flexible, and in thiscase, the tip angle may be a function of position within the particle.In either case, it may be preferred that particles stack with littleresin above or between them. Accordingly, the coating process, in oneexemplary embodiment of the present disclosure, may not attempt tocontrol the orientation of the particles in the resin (as in e.g.non-leafing pigment in a thick binder). Rather, the coating process mayproduce a dense stack of particles lying nominally in-plane at thesurface. High density in the thickness direction may substantiallyminimize particle tipping, the optical contribution of the binder, andadditional surface depth, which can trap light, produce shadowing,multiple scatter events and so on.

Applications

The present disclosure may be applied to manufacturing anyfront-projection surface, whether or not it is required to preservepolarization. In 3D cinema, such screens are typically manufacturedremotely, and then shipped and installed at the theatre. As described inthe embodiments of the present disclosure, the surfaces can be appliedto fixed structures on-site, either in temporary, single-event, orpermanent installations. Applications for single theatrical events maybe possible, in which a suitable structure such as a wall exists forapplication of the material, thus avoiding transportation of substrate,panels, and support structures. Prior to applying the final reflectivecoating, a sub-coat may be applied, which may planarize large featuresthat could otherwise significantly disrupt the particle surface normal.In a temporary installation, this may be a relatively thick coating withhigh surface tension. The thick coating may be removed after use.Alternatively, substrate material can be applied to an existingstructure using for example, a pressure sensitive adhesive, which may besubsequently coated with particles of the present disclosure.

In a web-based manufacturing of screen material, particles can berandomly distributed on a screen substrate, which may contain anadhesive layer. This layer may be, but is not limited to, a pressuresensitive adhesive, a thermally-activated material, or a similar form ofadhesive. The particles that contact the adhesive may be immediatelyadhered to the screen substrate, while those that do not contact theadhesive may be reclaimed. Other processes may be performed in aroll-to-roll process, such as, but not limited to, calendaring toflatten the material, encapsulation by a clear-coat, embossing and soon.

A benefit of the present disclosure may be the application toirregularly shaped surfaces, such as domes. Domes are particularlychallenging because they have compound curvature, making it difficult toapply a conventional planar screen. According to an embodiment, providedthat curvatures are small on the scale of a particle, front projectionsurfaces can thus be applied to any surface.

Generally, sound systems may be mounted behind the screen in frontprojection systems. This is the case for many cinema environments, andis also common in specialty installations and high-end home theatres.Acoustic transmission of most polymer substrates is good below one kHz,but begins to decrease at higher frequencies. To address this issue, anarray of through-holes may be typically used to raise acoustictransmission (e.g. 5-6 db of attenuation at 16 KHz). Conventionally,perforated/seamed substrate may be spray painted with ball-milledaluminum. Due to the relatively large perforation size relative toparticle size, there may not be a significant change in the diameter ofthe perforation as a consequence of coating.

High frequency acoustic transmission of a perforated substrate maydepend upon the pitch, and to a lesser degree, the diameter of the hole.Using spray coating or gel coating, the distribution of particlesdeposited on the surface may be random. Given that the particles may belarge relative to a perforation, the probability of covering overacoustic holes is significant. In the event that the particles andcoating are thin, some acoustic benefit may still exist. However, thearea fill-factor (ratio of metalized area to total area) of the coatingprocess may be controlled, and in practice, is difficult to drive intothe high 90% range fill factor. The random nature of the coating processcan thus be utilized to introduce a statistical distribution ofacoustically transparent openings. In order to substantially maximizethe probability that a void in the coating may produce an acousticopening, it may be preferred that the substrate is acousticallytransparent, or at least has a fine pitch. Candidate substrates mayinclude, but are not limited to, fine-pitch perforated polymers, anddense-weave fabrics of various fibers. In one embodiment, the substratemay be flat on the scale of a particle.

FIG. 6 is a flowchart illustrating operations of one embodiment of amethod for providing projection screens, in accordance with the presentdisclosure. Although the flowchart includes operations in a specificorder, it may be possible to perform the operations in a differentorder, and it also may be possible to omit operations as necessary. Theflow chart may begin with the operation of block 610, in which a firstsubstrate is provided. Next in the operation of block 620, a first sideof the first substrate may be embossed. Embossing the first side of thefirst substrate may be fabricated using any number of processes such asroll-to-roll UV embossing. In one embodiment, a first side of a secondsubstrate may be embossed. Continuing this embodiment, the firstsubstrate and the second substrate may be laminated together such thatthe embossed side of each substrate faces in an outwardly direction.

In the operation of block 630, a reflective layer may be deposited onthe embossed. The reflective layer may be any type of reflective coatingsuch as a metal including, but not limited to, aluminum. The reflectivelayer may be conformal to the embossed layer. Next, in the operation ofblock 640, an optical coating may be deposited subsequent to thereflective layer. The optical coating may passivate the reflective layerand may be a dielectric material such as, but not limited to, SiOx, MgF₂and so on. As previously discussed with respect to the operation ofblock 620, a second substrate may be embossed, and may also have areflective layer deposited on the embossed surface of the first side ofthe second substrate.

Next, in the operation of block 650, the structure produced by the firstsubstrate and the deposited layers may be cut into pieces to produceengineered particles. The engineered particles may be similar in size ormay be any combination of sizes. In one embodiment, the engineeredparticles may have a predetermined, targeted size of approximately onemillimeter. Additionally, the engineered particles may be cut into oneor more approximately, predetermined shapes. In one embodiment of thepresent disclosure, the engineered particles may be cut intoapproximately hexagonal shapes.

In the operation of block 660, the engineered particles may be combinedwith a fluid to produce a coating. As discussed with respect to FIG. 2,the fluid may include a transparent binder resin such as a transparentbinder resin such as, but not limited to PVC resin, enamel,polyurethane, acrylic, lacquer, and the like, and/or some form ofdilution. The fluid may function as a carrier for the engineeredparticles. Next, in the operation of block 670, the coating may betransferred to a substrate in a coating process. The coating process mayinclude spray painting or any spray and/or printing method known in theart.

As may be used herein, the terms “substantially,” “substantiallyapproximate(s),” “substantially minimize(s),” and “approximately”provide an industry-accepted tolerance for its corresponding term and/orrelativity between items. Such an industry-accepted tolerance rangesfrom less than one percent to ten percent and corresponds to, but is notlimited to, component values, angles, et cetera. Such relativity betweenitems ranges between less than one percent to ten percent.

While various embodiments in accordance with the principles disclosedherein have been described above, it should be understood that they havebeen presented by way of example only, and not limitation. Thus, thebreadth and scope of this disclosure should not be limited by any of theabove-described exemplary embodiments, but should be defined only inaccordance with any claims and their equivalents issuing from thisdisclosure. Furthermore, the above advantages and features are providedin described embodiments, but shall not limit the application of suchissued claims to processes and structures accomplishing any or all ofthe above advantages.

Additionally, the section headings herein are provided for consistencywith the suggestions under 37 CFR 1.77 or otherwise to provideorganizational cues. These headings shall not limit or characterize theinvention(s) set out in any claims that may issue from this disclosure.Specifically and by way of example, although the headings refer to a“Technical Field,” the claims should not be limited by the languagechosen under this heading to describe the so-called field. Further, adescription of a technology in the “Background” is not to be construedas an admission that certain technology is prior art to any invention(s)in this disclosure. Neither is the “Summary” to be considered as acharacterization of the invention(s) set forth in issued claims.Furthermore, any reference in this disclosure to “invention” in thesingular should not be used to argue that there is only a single pointof novelty in this disclosure. Multiple inventions may be set forthaccording to the limitations of the multiple claims issuing from thisdisclosure, and such claims accordingly define the invention(s), andtheir equivalents, that are protected thereby. In all instances, thescope of such claims shall be considered on their own merits in light ofthis disclosure, but should not be constrained by the headings set forthherein.

1. A method for providing a projection screen, the method comprising:embossing at least a first side of a first substrate to produce anoptically functional material; cutting the optically functional materialinto pieces to produce a plurality of engineered particles; combiningthe plurality of engineered particles with a binder to produce acoating; matching the refractive index of the first substrate and thebinder; and depositing the plurality of engineered particles on a secondsubstrate to produce a substantially homogeneous optical appearance ofthe projection screen.
 2. A method for providing a projection screen,the method comprising: embossing at least a first side of a firstsubstrate to produce an optically functional material; cutting theoptically functional material into pieces to produce a plurality ofengineered particles; and depositing the plurality of engineeredparticles on a second substrate to produce a substantially homogeneousoptical appearance of the projection screen, wherein the secondsubstrate has an adhesive layer.
 3. The method of claim 2, wherein theadhesive layer is a pressure sensitive adhesive.
 4. A method forproviding a projection screen, the method comprising: embossing at leasta first side of a first substrate to produce an optically functionalmaterial, wherein the first substrate has a thickness in the range offive to fifty microns; cutting the optically functional material intopieces to produce a plurality of engineered particles; and depositingthe plurality of engineered particles on a second substrate to produce asubstantially homogeneous optical appearance of the projection screen.5. A method for providing a projection screen, the method comprising:embossing at least a first side of a first substrate; embossing at leasta first side of a second substrate, wherein the first and secondsubstrate have a thickness range of 5 to 50 microns; laminating thefirst substrate and the second substrate together to produce anoptically functional material; cutting the optically functional materialinto pieces to produce engineered particles; and depositing theengineered particles on a third substrate to produce a substantiallyhomogeneous optical appearance of the projection screen.
 6. A method forproviding a projection screen, the method comprising: embossing at leasta first side of a first substrate; embossing at least a first side of asecond substrate; laminating the first substrate and the secondsubstrate together to produce an optically functional material;combining the plurality of engineered particles with a binder to producea coating; matching the refractive index of the first substrate and thebinder; cutting the optically functional material into pieces to produceengineered particles; and depositing the engineered particles on a thirdsubstrate to produce a substantially homogeneous optical appearance ofthe projection screen.
 7. A method for providing a projection screen,the method comprising: embossing at least a first side of a firstsubstrate; embossing at least a first side of a second substrate;wherein the second substrate has a adhesive layer; laminating the firstsubstrate and the second substrate together to produce an opticallyfunctional material; cutting the optically functional material intopieces to produce engineered particles; and depositing the engineeredparticles on a third substrate to produce a substantially homogeneousoptical appearance of the projection screen.
 8. The method of claim 7,wherein the adhesive layer is a pressure sensitive adhesive.
 9. Aprojection screen with a substantially homogeneous appearance, whereinthe substantially homogeneous appearance is achieved through webshuffling, the projection screen comprising: a first substrate; and acoating adjacent to the first substrate, the coating comprising aplurality of engineered particles produced by cutting an opticallyfunctional material into pieces, wherein the plurality of engineeredparticles are operable to primarily in behavior of light, furtherwherein the optically functional material further comprises a secondsubstrate has a thickness in the range of five to fifty microns.